You might want to do a little competitive research by clicking on the "Sponsors" button at the top of the page. Forum Sponsor Action Optics http://www.actionoptics.com/ has a primer on materials and styles. What's your price point? Who is your market? Fresh water guys need different features than salt fishermen.

That said, polarized lenses are critical. There is a safety factor to eye coverage when flies and lures with sharp hooks are flying, so more coverage, and wraparound coverage, is better than less. Form follows function. If you're going with light frames or polycarbonate lenses, consider the wind factor. No one likes losing glasses overboard. Make sure they'll stay on.

I'm not a potential customer; I have a pair of prescription glasses with progressive bifocal lenses so I can tie a knot close up and then look up and see at a distance. I like cable temples so I don't have to deal with Croakies or some gimp to tie the glasses around my neck. I like a sweat bar to keep perspiration and stinging sun block out of my eyes. My lenses are amber for salt water, but a trout fisherman might want gray.

I'd go to the websites for Cabelas, Orvis, LLBean, Offshore Angler, and some of the other outfitters to see what's already out there. Google is your friend. I'd use the search function on this board; your question has been asked and discussed before. For fishermen, good glasses are a tool, not a fashion statement.